Designing VxNbMoTa refractory high-entropy alloys with improved properties for high-temperature applications

Poor high/medium-temperature phase stability and/or low room-temperature ductility are currently bottlenecks of refractory high-entropy alloys (RHEAs) that restrict their high-temperature applications. Here, we explored novel VxNbMoTa RHEAs with vanadium concentrations of 0-25 at.%. VxNbMoTa RHEAs exhibit a single body-centered cubic (BCC) structure with unprecedented phase stability at a wide temperature range from solidus down to 350 degrees C. The grain structure of VxNbMoTa can be substantially refined when increasing the V concentration since higher V contents induce stronger solutal effects which contribute to higher growth restriction factors. Equimolar VNbMoTa exhibits the yield strength of 811 MPa at 1000 degrees C that is superior to most RHEAs reported by far, and this alloy also shows excellent roomtemperature ductility with the fracture strain > 25% and no strain-softening at high temperature, which is rarely seen in many popular RHEAs. These exceptional performances of VNbMoTa enable it to be a very promising material for high-temperature applications. (C) 2020 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Automated summary

The novel VxNbMoTa high-entropy alloys with vanadium concentrations of 0-25 at.% exhibit exceptional phase stability and high temperature strength, as well as excellent room-temperature ductility and resistance to high temperature deformation.